Method for reducing brightness reversion of mechanical pulps and high-yield chemical pulps

ABSTRACT

The present invention concerns a process for reducing the susceptibility of lignocellulosic material to unwanted yellowing, particularly yellowing caused by light and heat. According to the invention, the fibres are activated enzymatically or chemically and then contacted with a modifying agent capable of bonding to the oxidized fibre material, rendering the lignocellulosic fibre material improved resistance to brightness reversion. By means of the invention, brightness reversion caused by light or heat or a combination thereof can be retarded and even stopped.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fibrous products. In particular, thepresent invention concerns a process for reducing the susceptibility oflignocellulosic material to unwanted brightness reversion, in particularto brightness reversion caused by light or heat.

2. Description of Related Art

It is well-known in the art that light (UV light in particular), heat,moisture and chemicals can give rise to changes in the brightness ofcellulose pulps. Usually, such changes result in reduced reflectivity,particularly in blue light. This phenomenon is known as brightnessreversion or yellowing and can be caused by various factors depending onwhich type of pulp is concerned. Heat and damp are the main causes ofthe brightness reversion of chemical (lignin-free) pulps, whereasmechanical pulps mostly yellow when they are exposed to light. Thebrightness reversion of mechanical pulps also varies depending on theraw material (type of wood), production method (with or without chemicalpretreatment), and after-treatment (bleaching with different reagents)used. Thus, for instance, sulphonation and peroxide bleaching greatlyincrease the susceptibility of pulp to light-induced yellowing.

The brightness reversion of lignocellulosic pulps and products made fromsuch pulps can be reduced or even prevented in various ways, forinstance by means of impregnation or surface treatment using UV screens,antioxidants, or polymers, or by coating the surface with a coatinglayer or a layer of non-yellowing chemical pulp. Various additives aredescribed in the patent literature. Thus, U.S. Pat. No. 4,978,363discloses a composition and method for treating fibers based on amixture of an organopolysiloxane having at least one amino-substitutedhydrocarbon radical directly bonded to a silicon atom and a higher fattycarboxylic acid. The carboxylic acid reacts with the amino radicals toreduce yellowing and oxidation of the fiber treatment. The compositionand method provide non-yellowing fibers and a treatment agent that doesnot gel during use, such as when exposed to carbon dioxide and/or usedto treat carbon fibers.

U.S. Pat. No. 6,599,326 discloses inhibition of pulp and paper yellowingusing hydroxylamines and other coadditives. Chemical pulps or papers,especially kraft pulps or papers, which may still contain traces oflignin, have enhanced resistance to yellowing when they contain aneffective stabilizing amount of a N,N-dialkylhydroxylamine, an ester,amide or thio substituted N,N-dialkylhydroxylamine orN,N-dibenzylhydroxylamine or an ammonium salt thereof. This performanceis often further enhanced by the presence of one or more coadditivesselected from the group consisting of UV absorbers, polymericinhibitors, nitrones, fluorescent whitening agents and metal chelatingagents. Combinations of hydroxylamines or their salts, benzotriazole orbenzophenone UV absorbers and a metal chelating agent are, according tothe cited patent, considered particularly effective. As specificexamples, the patent mentions N,N-diethylhydroxylamine andN,N-dibenzyl-hydroxylamine.

Many of the additives that have been found to prevent yellowing areexpensive or problematic from an environmental point of view; others areonly effective when introduced in so large amounts that they may have anegative effect on other properties of the product or be uneconomical.Accordingly, there is still a need for methods of preventing yellowing

SUMMARY OF THE INVENTION

It is an aim of the present invention to eliminate the problems of theprior art and to provide a new method of reducing or preventingyellowing. The method aims at effectively reducing both light- andheat-induced brightness reversion of mechanical pulps and high-yieldchemical pulps.

The invention is based on the finding that the reactions that take placeduring oxidation, in particular enzymatic oxidation, of lignin appear tobe similar to the reactions that cause brightness reversion. Therefore,the initial reaction causing brightness reversion can be activated byenzymatic or chemical means and simultaneously immediately blocked bytargeted functionalization, by retarding or stopping the reactions.

Thus, the present invention provides a method of modifying fibres bybonding of new compounds to the oxidized fibres via radical pathways. Inparticular, the aim of the bonding of the compounds is to stabilize thestructure by forming a colourless lignin derivative unable toparticipate in yellowing reactions.

According to the invention, new fibrous products with modifiedproperties are produced by activating the fibres of the matrix with anoxidizing agent capable of oxidizing phenolic or similar structuralgroups, which may undergo reactions conducive to the formation ofcoloured sites on the fibres, and attaching to the oxidized sites atleast one modifying agent to block the reactivity of the oxidized sites.The activation is preferably carried out enzymatically although it isequally possible to use chemical agents for achievingoxidation/radicalization.

The modifying agent has at least one functional site or reactivestructure, which provides for binding of the modifying compound to thelignocellulosic fibre material, in particular at the oxidized phenolicgroups or corresponding chemical structures of the fibres, which havebeen oxidized during the activation step.

Based on the above, the present invention provides a process forproducing a fibre material having increased resistance to brightnessreversion, comprising a lignocellulosic fibrous matrix with phenolic orsimilar structural groups and a modifying agent reducing thesusceptibility of yellowing, including the steps of

-   -   reacting the lignocellulosic fibrous matrix with an oxidizing        agent in the presence of a catalyst capable of catalyzing the        oxidation of phenolic or similar structural groups by said        oxidizing agent to provide an oxidized fibre material, and    -   contacting the oxidized fibre material with a modifying agent        containing at least one first functional site, which is capable        of bonding to oxidized fibre material, said modifying agent        being capable of imparting to the lignocellulosic fibre material        improved resistance to brightness reversion caused by light or        heat or combinations thereof.

It should be noted that the term “catalyst” is to be given a broadinterpretation in the present context, and it covers any agent capableof possibly—but not exclusively—in combination with a separate oxidationagent, of achieving oxidation of the phenolic or similar groups.

Another embodiment of the invention provides a method of reducing lightor heat induced brightness reversion of mechanical or high-yieldchemical pulp, comprising the steps of enzymatically or chemicallyoxidizing phenolic groups of the pulp and bonding to the oxidizedphenolic groups a substance capable of forming a colourless ligninderivative unable to participate in yellowing reactions.

More specifically, the present invention is mainly characterized by whatis stated in the characterizing parts of claims 1 and 18.

The present invention provides important advantages. Importantly, theinvention makes it possible to produce novel kinds of fibrous materialshaving improved brightness reversion. By means of the process, themodifying agents can be reliable attached to the fibres, and theimproved resistance to yellowing will not be significantly impaired by,e.g., extensive washing of the fibres prior to forming the material intoa paper or cardboard web.

Further details and advantages of the invention will become apparentfrom the following detailed description and the appended workingexamples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depict in graphical form yellowing of spruce TMP samples asfunction of irradiation energy.

DETAILED DESCRIPTION OF THE INVENTION

As mentioned above, the invention generally relates to a method ofproducing fibre compositions with reduced susceptibility to yellowing.

The fibre matrix comprises fibres containing phenolic or similarstructural groups, which are capable of being oxidized by suitableoxidizing agents. Such fibres are typically “lignocellulosic” fibrematerials, which include fibre made of annual or perennial plants orwooden raw material by, for example, mechanical, chemimechanical orchemical pulping. During industrial refining of wood by, e.g., refinermechanical pulping (RMP), pressurized refiner mechanical pulping (PRMP),thermomechanical pulping (TMP), groundwood (GW) or pressurizedgroundwood (PGW) or chemithermomechanical pulping (CTMP), a woody rawmaterial, derived from different wood species as for example hardwoodand softwood species, is refined into fine fibres in processes, whichseparate the individual fibres from each other. The fibres are typicallysplit between the lamellas along the interlamellar lignin layer, leavinga fibre surface, which is at least partly covered with lignin orlignin-compounds having a phenolic basic structure

Within the scope of the present invention, also chemical pulps areincluded if they are susceptible to brightness reversion and have aresidual content of lignin sufficient to give at least a minimum amountof phenolic groups necessary for providing binding sites for themodifying agent. Generally, the concentration of lignin in the fibrematrix should be at least 0.1 wt-%, preferably at least about 1.0 wt-%.

In addition to paper- and paperboard-making pulps of the above kind,also other kinds of fibres of plant origin can be treated, such asbagasse, jute, flax and hemp.

An essential feature of the invention is to block brightness reversionby modifications of phenolic hydroxyls, alfa-carbonyls and/oralfa-hydroxyls on the fibres. In particular, by subjecting ligninstructures to enzymatic oxidation to yield oxidized groups of theaforesaid kind, the normal reactions causing brightness reversion can beattained. These reactions are then stopped by bonding a desired compoundto the activated, oxidized groups.

In the first stage of the present process, the lignocellulosic fibrematerial is reacted with a substance capable of catalyzing the oxidationof phenolic or similar structural groups to provide an oxidized fibrematerial. Typically, the substance is an enzyme and the enzymaticreaction is carried out by contacting the lignocellulosic fibre materialwith an oxidizing agent, which is capable—in the presence of theenzyme—of oxidizing the phenolic or similar structural groups to providean oxidized fibre material. Such oxidizing agents are selected from thegroup of oxygen and oxygen-containing gases, such as air, and hydrogenperoxide. Oxygen can be supplied by various means, such as efficientmixing, foaming, gases enriched with oxygen or oxygen supplied byenzymatic or chemical means, such as peroxides to the solution.Peroxides can be added or produced in situ.

According to an embodiment of the invention, the oxidative enzymescapable of catalyzing oxidation of phenolic groups, are selected from,e.g. the group of phenoloxidases (E.C.1.10.3.2 benzenediol:oxygenoxidoreductase) and catalyzing the oxidation of o- and p-substitutedphenolic hydroxyl and amino/amine groups in monomeric and polymericaromatic compounds. The oxidative reaction leads to the formation ofphenoxy radicals. Another groups of enzymes comprise the peroxidases andother oxidases. “Peroxidases” are enzymes, which catalyze oxidativereaction using hydrogen peroxide as their electron acceptor, whereas“oxidases” are enzymes, which catalyze oxidative reactions usingmolecular oxygen as their electron acceptor.

In the method of the present invention, the enzyme used may be forexample laccase, tyrosinase, peroxidase or oxidase, in particular, theenzyme is selected from the group of laccases (EC 1.10.3.2), catecholoxidases (EC 1.10.3.1), tyrosinases (EC 1.14.18.1), bilirubin oxidases(EC 1.3.3.5), horseradish peroxidase (EC 1.11.1.7), manganese peroxidase(EC 1.11.1.13) and lignin peroxidase (EC 1.11.1.14).

The amount of the enzyme is selected depending on the activity of theindividual enzyme and the desired effect on the fibre. Advantageously,the enzyme is employed in an amount of 0.0001 to 10 mg protein/g of drymatter fiber.

Different dosages can be used, but advantageously a dosage of about 1 to100,000 nkat/g, more advantageously 10-500 nkat/g.

In addition to enzymes, also chemical agents, such as alkali metalpersulphates and hydrogen peroxide and other per-compounds, can be usedfor achieving oxidization of the phenolic groups and for forming phenoxyradicals. The dosage of the chemical agent is, depending on the chemicalagent and on the pulp (i.e. on the amount of phenolic groups containedtherein), typically in the range of about 0.01 to 100 kg/ton, preferablyabout 0.1 to about 50 kg/ton, e.g. about 0.5 to 20 kg/ton. In the caseof chemical agents, no separate oxidation agent needs to be added. Theper-compound will achieve the aimed oxidation of the phonolic groups.

The activation treatment is carried out in a liquid medium, preferablyin an aqueous medium, such as in water or an aqueous solution, at atemperature in the range of 5 to 100° C., typically about 10 to 85° C.Normally, a temperature of 20-80° C. is preferred. The consistency ofthe pulp is, generally, 0.5 to 95% by weight, typically about 1 to 50%by weight, in particular about 2 to 40% by weight. The pH of the mediumis preferably slightly acidic, in particular the pH is about 2 to 10, inthe case of phenoloxidases. The chemical agents are usually employed atslightly acidic conditions, such as at pH 3 to 6. Peroxidases aretypically employed at pH of about 3 to 12. The reaction mixture isstirred during oxidation. Other enzymes can be used under similarconditions, preferably at pH 2-10.

In the second step of the process, a modifying agent capable of reducingthe susceptibility to yellowing of lignocellulosic fibres is bonded tothe oxidized phenolic or similar structural groups of the matrix. Such amodifying agent typically exhibits at least one first functional site,which is compatible with the fibrous matrix, and at least one secondfunctional site or structure providing for the above technical effect,as will be explained in more detail below.

The first functional site comprises in particular functional groups,which are capable of contacting and binding to the fibre at the oxidizedphenolic or similar structural groups or at its vicinity. The bondformed between the oxidized phenolic or similar residue can be covalentor ionic or even based on hydrogen bonding. Typical functionalities ofthe first functional site include reactive groups, such as hydroxyl(including phenolic hydroxy groups), carboxy, anhydride, aldehyde,ketone, amino, amine, amide, imine, imidine and derivatives and saltsthereof, to mention some examples. Also electronegative bonds, such ascarbon-to-carbon double bonds, carbon-to-hetero atom (e.g. C═N, C═O) aswell as oxo or azo-bridges can provide for bonding to the oxidizedresidues.

It is essential that the modifying agent is chemically or physicallybonded to the fibre matrix to such an extent that at least an essentialpart of it cannot be removed. One criterion, which can be applied totest this feature, is washing in aqueous medium, because often thefibrous matrix will be processed in an aqueous environment, and it isimportant that it retains the new and valuable properties even aftersuch processing. Thus, preferably, at least 10 mol-%, in particular atleast 20 mol-%, and preferably at least 30 mol-%, of the modifying agentremains attached to the matrix after washing or leaching in an aqueousmedium.

According to an embodiment of the invention, the modifying agent isactivated with an oxidizing agent.

The interaction of the oxidized lignocellulosic material and themodifying agent, resulting in bonding of the modifying agent to thelignocellulosic material, typically takes place in liquid phase, usuallyin water or in another aqueous medium. The pulp or other lignocellulosicfibrous matrix is suspended in the medium and it is contacted with themodifying agent or a precursor thereof, which is dissolved or dispersedin the same medium. The conditions can vary freely, although it ispreferred to carry out the contacting under mixing or stirring. Thetemperature is generally between the melting point and the boiling pointof the medium; preferably it is about 5 to 100° C. Depending on themodifying agent or its precursor, the pH of the medium can be neutral orweakly alkaline or acidic (pH typically about 2 to 12). It is preferredto avoid strongly alkaline or acidic conditions because they can causehydrolyzation of the fibrous matrix. Normal pressure (ambient pressure)is also preferred, although it is possible to carry out the processunder reduced or elevated pressure in pressure resistant equipment.Generally, the consistency of the fibrous material is about 0.5 to 95%by weight during the contacting stage.

According to a particularly preferred embodiment, the first and thesecond stages of the process are carried out in the same reactionmedium, without separating the fibrous matrix after the oxidation step.The conditions (consistency, temperature, pH, pressure) can, though,even in this embodiment be different during the various processingstages.

The first and the second stages of the process are carried outsequentially or simultaneously. However, it should be noted that thefirst step of the process aims at the formation in the fibrous substrateof phenoxy radicals, which are capable of binding modifying agents. Somemodifying agents will form substrates for the oxidative enzymes used inthe invention, and in that case, it is preferred to first add theoxidative enzymes and to allow the enzyme interact with the fibroussubstrate containing phenolic or similar groups, e.g. for 0.1 to 180minutes, in particular about 1 to 30 minutes to achieve oxidation of thephenolic groups, and to add the modifying agents after the enzymaticoxidation.

The same observations are true for the chemical oxidation agentsmentioned above. As Example 3 shows, reasonably good results areobtained with the simultaneous application of oxidation agent andmodifying agent, although the best results are attained when steps oneand two are carried our sequentially.

According to one preferred embodiment, the modifying agent is analiphatic or aromatic, monocyclic, bicyclic or tricyclic substance. Thealiphatic compound can be an unsaturated carboxylic acid, advantageouslya monocarboxylic unsaturated fatty acid, having 4 to 30 carbon atoms. Inparticular, the modifying agent can be a monocarboxylic, unsaturatedfatty acids containing a minimum of two double bonds, preferably twoconjugated double bonds. Such fatty acids have an even number of carbonatoms, typically in the range of 16 to 22. It is also possible to uselower alkanols, i.e. alcoholic compounds comprising 1 to 6, inparticular 1 to 4 carbon atoms. Examples include n- and i-propanol andn- and t-butanol.

Examples of particularly suitable compounds are constituted by linoleicand linolenic acid. It would appear that the unsaturated fatty acidbonds to the oxidized groups or structure via one of the double bonds.

Other suitable compounds include antioxidants, such as tocopherol andbeta-carotene.

The compound can have special properties, such as capability to trapradicals and form colourless substituents.

The above two steps can be carried sequentially or simultaneously. Alsoother compounds, such as papermaking chemicals may be present during thereaction steps.

After the above processing, the modified fibre having new properties isgenerally separated from the liquid reaction and further used in targetapplications.

The following non-limiting examples illustrate the invention:

EXAMPLE 1

A 5 g portion of bleached spruce TMP was suspended in water. The pH ofthe suspension was adjusted to pH 4.5 by addition of acid. Thesuspension was stirred at RT. Laccase dosage was 1000 nkat/g of pulp drymatter and the final pulp consistency was 7.5%. After 30 minutes laccasereaction, 0.15 mmol linoleic acid/g of pulp dry matter was added to thepulp suspension. After 1 h total reaction time, the pulp suspension wasfiltered and the pulp was washed thoroughly with water. Handsheets wereprepared. For comparison purposes, reference treatments were carried outusing the same procedure as described above but without addition oflaccase or linoleic acid or both. The light-fastness on the pulps wastested with Xenotest 150S light exposure and weathering test instrumentusing “window glass” filter. The brightness of the handsheets wasmeasured as function of irradiation dosage. The results are presentedgraphically in FIG. 1.

From the results presented in FIG. 1, it is apparent that the additionof linoleic acid and laccase was found to decrease the yellowingtendency of the pulp. In other words, addition of a modifying agent inthe presence of an oxidizing agent and a suitable catalyst, theyellowing tendency of pulp was decreased.

EXAMPLE 2

Bonding of New Compounds to TMP

A 5 g portion of spruce TMP was suspended in water. The pH of thesuspension was adjusted to pH 4.5 by addition of acid. The suspensionwas stirred at RT. Laccase dosage was 1000 nkat/g of pulp dry matter andthe final pulp consistency was 7.5%. After 30 minutes laccase reactionthe new compound was added to the pulp suspension. After 1 h totalreaction time, the pulp suspension was filtered and the pulp was washedthoroughly with water. Handsheets were prepared. For comparisonpurposes, reference treatments were carried out using the same procedureas described above but without addition of laccase or the new compound.The light-fastness on the pulps was tested with Xenotest 150S lightexposure and weathering test instrument using “window glass” filter. Thechanges in the ISO brightnesses after irradiation are summarized inTable 1. TABLE 1 Δ Brightness Irradation (as ISO- Treatment (Whm²)Brightness) TMP Reference 1260 10 TMP + laccase + ferulic acid (0.15mmol/g) 1260 3 TMP + laccase + vinyl laurate (0.3 mmol/g) 1260 2

EXAMPLE 3

Sample A: Peroxide bleached aspen-CTMP-pulp was treated with sodiumpersulphate (dosage 5 kg/ton of pulp) and linoleic acid (5 kg) at 80°C., at pH 5 for 60 minutes. The treatment was carried out at aconsistency of 10%.

Sample B: The pulp sample was treated in the same way as Sample A exceptthat ammonium persulphate (5 kg) was used instead of Na-persulphate.

Sample C: The pulp sample was treated in the same way as Samples A and Bexcept that hydrogen peroxide was used instead of persulphate. The pH ofthe test was 4.

Sample D: The pulp sample was treated as Sample A but t-butanol (5 kg)was used instead of linoleic acid.

Sample E: The pulp sample was treated in the same way as Sample A, butno linoleic was added. After the treatment with persulphate, a separatetreatment was made with linoleic acid (5 kg) at 80° C. at a consistencyof 10%. The duration of the treatment was 30 min, and the pH was 5

Sample F: The sample was prepared as Sample D, but without using anyt-butanol. After the persulphate treatment, a separate treatment (30min, pH 5) with t-butanol was carried out at a consistency of 10% and atemperature of 80° C., the dosage being 5 kg/ton of pulp.

Sheets were manufactured from the pulp samples and their brightnessstability was tested with a Xenotest S150 using a “window pane” filter.The radiation of the Xenotest-apparatus corresponded to that of sunlightthrough a window pane, but the intensity of the radiation was muchstronger (accelerated test). The brightness of the samples wasdetermined after a 2 h radiation (corresponds to 1260 wh/m²)

The results are indicated in Table 2 below: TABLE 2 Sample Brightnessreduction (Δ Brightness, % ISO) Reference (untreated) 10.4 A 6.9 B 7.2 C6.8 D 7.2 E 6.1 F 6.1

As apparent from the above results, the brightness stability of thesamples treated by the present invention has been improved by even morethan 4 units.

1. A process for producing a fibre material having reducedsusceptibility to yellowing, comprising activating the fibres of thematrix with an oxidizing agent capable of oxidizing phenolic or similarstructural groups, which may undergo reactions conducive to theformation of coloured sites on the fibres, and attaching to the oxidizedsites at least one modifying agent to block the reactivity of theoxidized sites.
 2. The process according to claim 1, wherein activationis carried out enzymatically or chemically.
 3. The process according toclaim 1, comprising the steps of reacting the lignocellulosic fibrousmatrix with an oxidizing agent in the presence of a catalyst capable ofcatalyzing the oxidation of phenolic or similar structural groups bysaid oxidizing agent to provide an oxidized fibre material, andcontacting the oxidized fibre material with a modifying agent containingat least one first functional portion, which is compatible with theoxidized fibre material, said modifying agent being capable of providingthe lignocellulosic fibre material with properties reducingsusceptibility to yellowing.
 4. The process according to claim 3,wherein the modifying agent is activated with an oxidizing agent.
 5. Theprocess according to claim 1, wherein the modifying agent is abrightness reversion inhibitor.
 6. The process according to claim 1,wherein the modifying agent is selected from the group comprising C₁₋₄alkanols, unsaturated carboxylic acids, monocarboxylic unsaturated fattyacids, and monocarboxylic unsaturated fatty acids containing a minimumof two double bonds, preferably two conjugated double bonds.
 7. Theprocess according to claim 6, wherein the modifying agent is linoleicacid or linolenic acid.
 8. The process according to claim 1, wherein themodifying agent is selected from the group of antioxidants.
 9. Theprocess according to claim 1, wherein the catalyst capable of catalyzingthe oxidation of phenolic or similar structural groups is an enzyme oran chemical agent.
 10. The process according to claim 9, wherein theenzyme capable of catalyzing the oxidation of phenolic or similarstructural groups is selected from the group of peroxidases andoxidases.
 11. The process according to claim 10, wherein the enzyme isselected the group of laccases (EC 1.10.3.2), catechol oxidases (EC1.10.3.1), tyrosinases (EC 1.14.18.1), bilirubin oxidases (EC 1.3.3.5),horseradish peroxidase (EC 1.11.1.7), manganese peroxidase (EC1.11.1.13) and lignin peroxidase (EC 1.11.1.14).
 12. The processaccording to claim 1, wherein the enzyme dosage is about 1 to 100,000nkat/g, preferably 10-500 nkat/g, and it is employed in an amount of0.0001 to 10 mg protein/g of dry matter.
 13. The process according toclaim 9, wherein the chemical agent is selected from the group ofper-compounds, in particular from the group consisting of alkali metalpersulphates and hydrogen peroxide.
 14. The process according to claim1, wherein the oxidizing agent is selected from the group of oxygen,hydrogen peroxide and oxygen-containing gases, such as air.
 15. Theprocess according to claim 1, wherein oxygen or oxygen-containing gas isintroduced into the aqueous slurry during the reaction.
 16. The processaccording to claim 1, wherein the reaction of step (a) is carried out inan aqueous or dry phase at a consistency of 1 to 95% by weight,preferably about 2 to 40% by weight, of the fibre material.
 17. Theprocess according to claim 1, wherein the reaction is carried out attemperature in the range of from 5 to 100° C.
 18. Method of reducinglight or heat induced brightness reversion of mechanical or high-yieldchemical pulp, comprising the steps of enzymatically or chemicallyoxidizing phenolic groups of the pulp and bonding to the oxidizedphenolic groups a substance capable of forming a colourless ligninderivative unable to participate in yellowing reactions.
 19. The processaccording to claim 1, wherein the reaction steps are carried outsequentially or simultaneously.